The present invention relates to printing members useable in a variety of printing presses, such as, gravure, offset, silk screen, flexo and others and to methods for producing same. The term printing members refers throughout the specification and claims to printing members used in printing presses operating with an inking fluid. The invention also applies to printed circuit board (PCB) members.
There are two types of printing members typically used in state of the art printing presses, such as gravure, offset screen and flexo printing presses and described in FIGS. 1A through 2B. The printing member of FIG. 1A, generally referenced 10, comprises a base layer 2 and a Ultra Violet (UV) curable layer 4. The member 10 is being recorded by applying a mask 6, as also indicated by step 12 (FIG. 1B). The member is being flood exposed to UV light, the mask blocks the UV light from certain parts of the member, the exposed parts 8 are polymerized (step 14 of FIG. 1B), the mask is then being removed (step 16 in FIG. 1B) and the member 10 is being cleaned so that non exposed areas 7 are removed by washing (step 18 in FIG. 1).
In the Example of FIG. 2A, the mask forms part of the printing member 20. The member 20 comprises a base layer 22 and a UV curable layer 24 witch may be similar to layers 2 and 4 (FIG. 1A). The layer 24 is being coated with an Infra Red (IR) absorbable UV blocking material 26 (see also 32 in FIG. 2B which represents the member 20 ready for recording), the image is being ablated in a digital pixel by pixel fashion (step 34 of FIG. 2B) and subsequently the entire member is flood exposed to UV light (step 36 of FIG. 2B) which hardens (polymerizes) the areas 28 from which the coating 26 has been removed. The unexposed areas 23 are removed by cleaning thus providing the printing member 20.
During printing with both printing members 10 and 20 ink is first applied to the printing member (step 31 of FIG. 3B) and then transferred to the substrate 35 (FIG. 3A) as also indicated in step 33.
These types of printing members are also used not as printing members but as Printed Circuit Boards (PCB) members with the addition of a conductive layer. These two types of members are collectively referred to hereinafter as member or members.
The present invention provides a printing or PCB member. In on preferred embodiment, the member includes a topmost protective layer, an IR ablatable layer disposed above the topmost protective layer, a substrate and a washoff layer intermediate the topmost protective layer and the substrate. The wash-off layer is washed with a solvent after imagewise ablation of the topmost protective layer so as to expose the substrate, so that a printing member is produced.
In another preferred embodiment, the IR ablatable layer is disposed below the topmost protective layer.
In yet another preferred embodiment of the present invention, the topmost protective layer and the IR ablatable layer are combined in one layer.
Further, in accordance with a preferred embodiment of the present invention, the IR ablatable layer includes a resinous binder combined with an Infra Red absorbing dye or pigment or resins such as acrylics or polyurethanes with carbon black dispersed in resin or nigrosine dissolved in the resinous solution before deposition.
Still further, in accordance with a preferred embodiment of the present invention, the thickness of the IR ablatable layer is generally between 0.01 and 5 microns.
Additionally, in accordance with a preferred embodiment of the present invention, the protective layer includes a binder resin which is insoluble in the solvent used for wash out either by its nature or by reason of the cross-linking of the resin during the deposition of the layer or a sheet of polymer or the protective layer has been derived from a cross-linkable water soluble melamine derivative plus a suitable cross-linking material such as toluene sulphonic acid, or an aqueous dispersion of polyurethane, cross-linked with a suitable cross-linking material.
Still further, in accordance with a preferred embodiment of the present invention, the thickness of the protective layer is generally between 0.2 and 5 microns.
Moreover, in accordance with a preferred embodiment of the present invention, the combined layer includes a polysiloxane resin loaded with an Infra Red absorbing dye or pigment.
There is also provided in accordance with a preferred embodiment of the present invention a printing member wherein the washoff layer comprises UV curable materials and includes an alkali soluble rosin maleic resin esterified with pentaerythritol, an acrylate oligomer, a monomer-acrylate or methacrylate and a photoinitiator such as hydroxymethyl phenylpropane.
Still further, in accordance with a preferred embodiment of the present invention, the thickness of the washoff layer is generally between 0.2 microns and 5 mm.
Further, in accordance with a preferred embodiment of the present invention, the substrate is selected from the group of polyester, aluminum, anodized aluminum or copper cladded glass/epoxy resin.
There is also provided in accordance with a preferred embodiment of the present invention a printing member wherein the member is a gravure printing member and wherein the thickness of the IR ablatable layer is generally between 0.01 to 5 microns, the thickness of the protective layer is generally between 0.2 to 5 microns, the thickness of the wash-off layer is generally between 30-200 microns, and the thickness of the substrate is between 100-3,000 microns.
There is also provided in accordance with a preferred embodiment of the present invention a printing member wherein the member is an offset printing member and wherein the thickness of the IR ablatable layer is generally between 0.1 to 5 microns, the thickness of the protective layer is generally between 0.2 to 5 micron, the thickness of the wash-off layer is generally between 0.1 to 1 micron, and the thickness of the substrate is between 150-800 microns.
Additionally, in accordance with a preferred embodiment of the present invention, there is provided a printing member wherein the member is a screen printing member, the substrate being a screen of woven polyester, cellulose fiber, nylon or stainless steel.
Still further, in accordance with a preferred embodiment of the present invention, there is provided a screen printing member wherein the thickness of the IR ablatable layer is generally between 0.1 to 5 microns, the thickness of the protective layer is generally between 0.2 to 5 micron, the thickness of the wash-off layer is generally between 0.1 to 5 micron, and the thickness of the substrate is between 50-300 microns, and wherein the wash off layer is within the material of screen or a screen printing wherein the thickness of the IR ablatable layer is generally between 0.01 to 5 microns, the thickness of the protective layer is generally between 0.2 to 5 micron and the thickness of the wash-off layer is generally between 0.1 to 5 microns.
There is also provided in accordance with a preferred embodiment of the present invention a printing member wherein the member is a printed circuit board member or a flexo printing member.
Methods for producing the members of the present invention are also disclosed, in a preferred embodiment, the method includes the step of providing the member of the present invention, exposing it to imagewise IR radiation so as to ablate the IR absorbing layer and the protective layer and washing off the washoff layer so as to expose the substrate whereby the member ready to be used as a PCB or a printing member is ready for use.
Further, in accordance with a preferred embodiment of the present invention, the step of washing further including the step of mechanically removing the wash-off layer.
Moreover, in accordance with a preferred embodiment of the present invention, the method also includes the step of UV curing the member after said step of washing.
Still further, in accordance with a preferred embodiment of the present invention, the member also includes a conductive layer and the method further includes the step of etching the electrically conductive layer after the step of washing.
Furthermore, in accordance with a preferred embodiment of the present invention, the method further comprises the step of a second washing after the step of etching.